public async Task <IHttpActionResult> PutRate([FromUri] Guid id, [FromBody] JewelRate rate)
        {
            if (!ModelState.IsValid)
            {
                return(BadRequest(ModelState));
            }

            if (id != rate.Id)
            {
                return(BadRequest());
            }

            db.Entry(rate).State = EntityState.Modified;

            try
            {
                await db.SaveChangesAsync();
            }
            catch (DbUpdateConcurrencyException)
            {
                if (!RateExists(id))
                {
                    return(NotFound());
                }
                else
                {
                    throw;
                }
            }

            return(Ok());
        }
        public async Task <IHttpActionResult> PostRates(JewelRate rate)
        {
            if (!ModelState.IsValid)
            {
                return(BadRequest(ModelState));
            }
            rate.Id = Guid.NewGuid();
            db.JewelRates.Add(rate);
            await db.SaveChangesAsync();

            return(Ok());
        }
        public async Task <IHttpActionResult> DeleteBook(Guid id)
        {
            JewelRate rate = await db.JewelRates.FindAsync(id);

            if (rate == null)
            {
                return(NotFound());
            }

            db.JewelRates.Remove(rate);
            await db.SaveChangesAsync();

            return(Ok(rate));
        }